Series-type distributing system.



H. n. BRALEY. SERIES TYPE DISTRIBUTING SYSTEM. APPIICATION FILED JULY 25. I917- 1 ,300;242, w Patented Apr. 15,1919.

nizzzzz'r WITNESSES: INVENTOR Howard!) Bra/6y o o o 0 o o I BY I 6a A TTORNEY -UNITED STATES PATENT OFFICE.

HOWARD D. BRALEY, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA.

SERIES-TYPE DISTRIBUTING SYSTEM.

Specification of Letters Patent.

Patented Apr. 15, 1919.

Application filed July 28, 1917. Serial No. 183,361.

To all whom it may concern:

Be it known that I, HOWARD D. citizen of the United States, of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Series-Type Distributing Systems, of which the following is a specification.

y invention relates to distributing systems of the type wherein electrical energy is transferred through a high-voltage, constant-current circuit and distributed therefrom through series or current transformers, and it has for its object to provide a system of the character designated wherein the ultimate load circuits shall be maintained at relatively low voltage and, furthermore, shall not be subject to abnormal currents in case of accidental grounding.

In the accompanying drawing, Figure 1 is a side view of a composite transformer, partially in section and partially in elevation, together with associated supply and load circuits, illustrating a preferred form of my invention; Figs. 2 and 3 are simplified diagrammatic views illustrating the operation of the system of Fig. 1; and Fig. 4 is a diagrammatic view of a modification of the system shown in Fig. 1, and embodying two distinct transformer members.

Systems of electrical distribution, particularly adapted for electric lighting, as on ridges and streets, are well known wherein the energy is transferred overa high-voltage, constant-current circuit and is distributed through a plurality of low voltage circuits inductively interlinked. therewith through current or series transformers. It is usual to ground these local distributing circuits at one point, preferably the mid point of the secondary winding of the transformer supplying energy thereto, whereby the potential of no point in the local distributing circuit can exceed one-half the electromotive force of the secondary winding of the associated transformer. When a load circuit of this character is accidentally grounded at a point other than the mid point of the load thereof, two local circuits are formed and there is a tendency for theproduction of an excessive amount of current in the local circuit including the smaller portion of the load, which may result in the burning out of the lamps therein.

In accordance with my invention, I pro- BRALEY, a and a resident vide means whereby the transformer fluxes are so distributed under abnormal conditions as to maintain substantially the desired current in all portions of the load, irrespective provided with a third leg or cross piece 7 rlmary windings 8 and 9 are, disposed on the right and left leg members of the core 6 and are connected in series relation to a constant-current, high-voltage supply circuit 10. Secondary windings 11 and 12 are respectively associated with the primary windings 8 and 9 and are connected in series relation to a load circuit 13 shown as comprising a plurality of seriesoonnected electric lights. The secondary circuit is grounded between the windings 11 and 12, as indicated at 14. The system thus described is shown diagrammatically in Fig. 2.

Having thus described the arrangement of a system embodying my invention, the normal operation is as follows. Upon supplying current through the system 10, the two transformer aggregates formed by the windings 8 andll and the windings 9 and 12. respectively, are equally energized and tend to produce equal working fluxes. Said working fluxes traverse the core member 6 in series relation, the flux of each transformer aggregate traversing the windings of the other aggregate. The opposite ends of the cross piece 7 are at equal magnetic potential and no flux flows therethrough. The mid pointv of the load 13 is at ground potential and the maximum potential of any point in the 'load'circuit is that of one transformer aggregate.

Let it now be assumed that the load circuit is accidentally grounded at an unsymmetrically located point, as at 15. A current path is thus provided between the points 14 and 15, as indicated by a dotted line in Fig. 3, and two distinct load circuits are formed aving unequal loads therein. the left-hand load circuit including but three light units, whereas the right-hand load circuit includes eight light units. Were the transformer aggregates mounted as shown ona core memrespectively,

' tion of a lower voltage in ber having no middle leg 7, they would continue to have the same total flux, as the flux of one would thread the other. The flux of the right-hand transformer would tend to be much stronger than that of the left-hand transformer aggregate and this flux traversing the left-hand transformer would tend to produce a far higher voltage in the winding 11 than normally required by the three light units to the left of the point 15, with a consequent increase in current above normal, the correlative action resulting in the producthe winding 12 than is required.by the eight light units to the right of the point 15 and a consequent decrease in current below normal value.

The action of the core leg 7, however, is such that upon a difference in the loads imposed upon the two transformer aggregates, a difference of magnetic potential is at once produced between the ends thereof. A large part of the excess magnetic flux of either transformer aggregate flows through the leg 7 and hence does not afiect the other ag gregate. The proportion of the excess flux produced by either transformer aggregate which passes through the leg 7 is controlled by the cross section and permeability of the leg 7 as compared with the cross-section and permeability of the legs inclosed by th coils. Thus, under the conditions assumed in Fig. 3, the flux of the windings 9 and 12 would tend to be greater than that of the windings 8 and 11 but substantially all of the excess flux of the windings 9 and 12 traverses the member 7 and thus prevented from traversing the winding 11 wherein it would produce a sufliciently high current to damage the three light units at the left of the point 15. A similar action will take place upon accidentalgrounding at any point on the load circuit.

7 In the system of Fig. 4, two distinct current transformers 16 and 17 are employed having their primary windings inserted in the supply circuit and having their secondary windings connected in series relationin the load circuit, as before, the load circuit being grounded at the point 17 intermediate the secondary windings. Under these conditions, the accidental grounding of any point of the load circuit merely subdivides the load circuit and permits the two-load transformers to operate independently. It is obvious, however, that the structure of Fig. 1 provides a similar result with the use of more compact, lighter and less expensive apparatus.

'While-I have shown my invention in a plurality of preferred forms, it will be ob vious to those skilled in the art that it is susceptible of various other minor changes and modifications without departing from the spirit thereof andI desire, therefore, that only suchlimitations! shall be placed.

thereupon as are imposed by the prior art or as are indicated in the appended claims.

I claim as my'inve'ntion: I

1. A distributing system comprising a substantially constant-current circuit, a current transformer provided with split primary and secondary windings and havin said primary windings inserted in said clrcuit, a load circuit connected to said secondary windings, a ground connection between the two halves of said secondary winding, and means in said transformer providing a flux path for a portion'of the excess magnetizing flux of one half of the primary winding over that of the other half thereof. 7

2. A distributing system comprising a substantially constantcurrent supply circuit, a transformer provided with two primary and two secondary windings,each of said primary windings being mounted in relative magnetic proximity to one of said secondary windings, respectively, and one primary winding, together with its associated secondary winding being spaced away from the other primary winding and its associated winding and with means for providing a magnetic path for a portion of the excess. magnetizing flux of one primary winding. over that of theoother primary winding, said path'being-magnetically independent of said other primary winding, connections for inserting said primary windings in saidsupply circuit, a series load circuit including both of said secondary windings, and a ground connection intermediate to said secondary windings.

3. A distributing system comprising a substantially constant-current supply circuit, a transformer comprisinga closed-core member provided with a primary winding and a closely associated secondary winding, an additional primary winding and closely asso ciated secondary winding disposed substantially diametrically opposite said first named windings and a core member diametrically disposed across said closed-core member between said two pairs of windings, connections for inserting said primary windings in series relation in said supply circuit, a load circuit including said two secondary windings in series relation, and a ground connection intermediate said secondary wind-.

i. A distributing system comprising asubstantially constant-current supply circuit, a transformer comprising two distinct and normally equivalent transformer aggregates so disposed that their magnetomotive forces operate in series relation upon a commonv closed magnetic core member, a core member so disposed as to receive a portion of. the excess flux of one transformer aggregate over that of the other, said excess'flux; being thereby diverted from traversing said other transformer aggregate, connections-for 130 inserting the primary windings of said transformer aggregates in said supply circuit, a load circuit including the secondary windings of both transformer aggregates, and a ground connection intermediate to said secondary windings.

5. In an electrical distributing system, a closed load circuit subject to grounding at an unsymmetrically disposed point in the load thereof, two current transformer aggregates having their secondary windings connected in electrical proximity in said load circuit for supplying energy thereto, and a ground connection between said secondary windings, said transformer aggregates being so assembled upon a common core member that when the fluxes thereof are equal, said fluxes traverse both. transformer aggregates, and when said fluxes are unequal, a portion of the excess flux of either aggregate does not traverse the other aggregate.

6. In an electrical distributing system, a closed load circuit subject to grounding at an unsymmetrically disposed point in the load thereof, two current transformer aggregates having their secondary windings connected in electrical proximity in said load circuit for supplying energy thereto, and a ground connection between said secondary windings, said transformer aggregates being respectively disposed upon the outer portions of the loops of a core member of substantially figure 8 configuration, whereby when the fluxes thereof are equal, the opposite ends of the cross piece of said core member are at equal magnetic potential and substantially all the flux of one aggregate traverses the other aggregate and when the fluxes of said aggregates are unequal, a portion of the excess flux traverses said cross piece without traversing the aggregate having a flux deficiency.

In testimony whereof, I have hereunto subscribed my name this 17th day of July 1917.

HOWARD 'n. BRALEY.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. G." 

